Circuitry for generating linear and temperature dependent signals are generally known and widely used in the electronics industry. Such circuitry is often required to compensate for inherent temperature dependencies in systems utilizing one or more transducers formed of piezoresistive sensing elements, wherein a temperature dependent signal of the form: EQU F(T)=KX*(T-TN) (1)
is typically required. In equation (1), KX is the slope of F(T) versus temperature and TN is a reference temperature at which F(T) is equal to zero.
While circuits capable of generating F(T) signals in accordance with equation (1) have been successfully used in the past, all such known circuits have drawbacks associated therewith. For example, in all such known circuits, KX is independent of supply voltage (hereinafter referred to as VDD). Thus, in applications where system output scaling with VDD is required, all circuitry utilizing the F(T) signal must likewise operate independently of VDD. Eventually, however, the system output signal must be multiplied by a factor of VDD in order to avoid excessive ratiometricity errors at temperatures other than TN.
Requiring all circuitry utilizing the F(T) signal to operate independently of VDD typically necessitates incorporation of complicated bandgap circuitry therein. What is therefore needed is a signal generating circuit operable to generate an F(T) signal in accordance with equation (1), wherein the slope term (KX) is temperature dependent. Such a circuit would simplify the design of subsequent circuitry utilizing the F(T) signal by eliminating the need for the inclusion of bandgap circuitry therein to achieve VDD independence.